Change ui::Event::time_stamp from TimeDelta to TimeTicks

ash/system/toast/toast_manager_unittest.cc

Index: ash/system/toast/toast_manager_unittest.cc
diff --git a/ash/system/toast/toast_manager_unittest.cc b/ash/system/toast/toast_manager_unittest.cc
index fc6ec7f6941e209ee3e12b47cd72112ffa0a6f35..b813fd0dbafe1aaab70975cffb4493c050738eb2 100644
--- a/ash/system/toast/toast_manager_unittest.cc
+++ b/ash/system/toast/toast_manager_unittest.cc
@@ -19,7 +19,7 @@ const int64_t kLongLongDuration = INT64_MAX;
 
 class DummyEvent : public ui::Event {
  public:
-  DummyEvent() : Event(ui::ET_UNKNOWN, base::TimeDelta(), 0) {}
+  DummyEvent() : Event(ui::ET_UNKNOWN, base::TimeTicks(), 0) {}
   ~DummyEvent() override {}
 };